For example, as shown in FIG. 3 of PTL 1, in a turbo refrigeration apparatus which is used for a heat source of district heating and cooling, drum shell-shaped condenser and evaporator are installed to be parallel to each other along with one or a plurality of turbo compressor, and an economizer which gas-liquid separation and intermediate cooling of a refrigerant are disposed around the condenser or evaporator. In a turbo refrigeration apparatus which uses a high-pressure refrigerant of R134a or the like, that is, a refrigerant used at a maximum pressure of 0.2 MPaG or more, the economizer is also formed in a drum shell shape in order to secure strength.